Over the past decade as oil has become scarcer, the desirability and need to look offshore for additional sources of oil and gas has increased and offshore oil drilling platforms or installations have become very common. Normally crews of upwards of sixty people are employed to operate one of these offshore installations and accordingly a great deal of resupply capability is required. Crews are periodically changed and there is a daily need for food, water and fuel, as well as for boats capable of fighting fires as well as other general purpose work needed. As a result, a variety of various types of vessels have been developed which have been uniquely suited for particular ones of those tasks. In that regard, separate and specifically designed boats have been designed for hauling fuel, others for hauling water, and still others for fighting fires and for running between off-shore installations. Some of these can also carry crews and most include an open cargo deck for hauling crated materials. This has necessitated the use of wide variety of vessels each type being normally leased by oil companies at fairly high rates.
Such boats vary in lengths from 60 to 135 feet and some, in outward appearance and design, are somewhat similar to World War II PT boats, such as set forth and described in Scott-Paine, U.S. Pat. No. 2,288,490. Two patents which show exemplary types of currently used crew boats are Keenan, U.S. Pat. No. Des. 219,556 and McMakin, U.S. Pat. No. 4,156,577.
Scott-Paine discloses a high speed motor boat that has a planing type hull which runs aft from midships and a flared V-shaped hull which runs forward. This boat is of a hard-chine type and is provided with a high free-board forward and a low free-board aft. The chine line dihedral angles from midships aft decrease gradually and the bottom surfaces of the boat from midships aft have a concave cross-section which likewise decreases gradually until the bottom sides are substantially flat near the stern.
Accordingly, when the boat is both loaded and unloaded, the boat lies at an angle other than one that would position the boat substantially horizontal with the surface of the water so that the stern has a deeper draft than the bow. By having the center of gravity substantially at the same point as the center of pressure at the hull, the high free-board condition of forward portion will remain thereby providing a hull that will bore through waves when running at high speed improving the high speed sea worthiness of the vessel.
Keenan and McMakin disclose crew or supply boats which have a deck house in the forward portion and a fairly expansive exposed rear deck area for carrying cargo. As it was true with the Scott-Paine boat discussed above, the chine lines on these boats appear to gradually decrease or fall toward the stern so that when loaded, the forward end of the vessel will rise up while the rear or aft portion of the vessel, which supports the load carried by the exposed decking will fall such that the load is supported.
Neither of these boats or patents suggest the particular combination of elements as set forth herein nor the hull configuration of the present invention, nor that it is possible, with a change in hull design, to include a wide variety of material and liquid handling capabilities such that one supply vessel can perform a variety of functions.
The hull configuration used on known crew boats can support fairly heavy loads on the exposed, rear portion of decking, but it is important for the stern end of these vessels to ride fairly low in the water, not only so that the hull can support the weight on the deck, but so that the propeller, rudder and other control surfaces remain fully in contact with the water during running. Accordingly, to load such known prior art vessels in any other manner especially one that would place additional weight on the forward part of the vessel would disrupt the ability of the boat to properly plane and would jeopardize the boat's proper and desired operation.
Applicants are also aware of Johnson, U.S. Pat. No. 2,244,011, that relates to the construction of a small, wooden boat which includes reinforcing of the hull near the keel area that provides additional storage space on the bottom of the boat for containing the onboard fuel supply for running the engine powering the boat.
Despite this art and the fact that crew boats have been used for some years to supply offshore facilities, none of the crew boats of which applicants are aware have multiple capabilities for performing a variety of tasks nor could such boats be modified to enable them therefor.